Enhancing the surface integrity and corrosion resistance of Ti-6Al-4V titanium alloy through cryogenic burnishing

In the surface layer of Ti-6Al-4V titanium alloy bar produced by cryogenic burnishing, reduced surface roughness, refined grain structure, and an obviously improved corrosion resistance are achieved. The surface roughness of cryogenic burnished sample was much lower than that of dry burnished sample. A nanocrystalline layer was fabricated on Ti-6Al-4V titanium alloy by cryogenic burnishing. There was a significant impact of the number of passes on structural refinement. The corrosion behavior of samples before and after cryogenic burnishing in a 0.9 % NaCl solution was investigated by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and Mott-Schottky measurements. Ti-6Al-4V alloy with nanocrystalline layer has better corrosion resistance than the unburnished coarse-grained counterpart. The positive effect can be explained by the more rapid, stable, and less defective passive film formed on the surface nanocrystalline layer of Ti-6Al-4V alloy due to its high density of grain boundaries and dislocations.